The present invention relates generally to taps which extract electromagnetic energy from transmission lines and specifically taps which extract electromagnetic energy from transmission lines and which couple the electromagnetic energy to other transmission lines.
This application concerns the invention of a tap designed to be mounted on a to coaxial Radio Frequency (RF) communications feeder cable. The tap presents minimal degradation to the cable""s performance, while maintaining uniform coupling over a multi-octave bandwidth. The tap does not require a splice.
Our following prior U.S. patents disclose taps of this general type:
xe2x80x9cA Tap For Extracting Energy From Transmission Lines Using Impedance Transformers,xe2x80x9d U.S. Pat. No. 5,729,184, by inventors W. Paxman and R. Stein; and
xe2x80x9cA Tap For Extracting Energy From Transmission Lines,xe2x80x9d U.S. Pat. No. 5,689,218, by inventors R. Stein and W. Paxman.
Most taps currently on the market are relatively narrow band or have high-insertion-loss sections (thru) between the wide band limits. Another problem with most taps on the market today is the potential of damaging the tap during installation. One particular difficulty is the connection of a feeder or jumper cable to the tap after it is installed. Tightening the connector places stress on the tap and its mounting, damaging it.
The previous inventions by R. Stein and W. Paxman (cited above) describe taps for coaxial transmission lines using cross-connected couplers and impedance transformers with matching resistors, respectively. The current invention is based on the impedance transformer principle of the prior art, with dramatic performance and cost improvements.
It is an object of the invention to provide a method of transforming the load impedance of a tap such that the tap engenders low losses in the host cable and operates over an increased coupling bandwidth.
Another object of the invention is to provide an assembly for the tap that is simple, inexpensive to manufacture and use, and rugged in operation, and does not require separate installation of a feeder or jumper cable.
Other aspects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings.
In accordance with the present invention, the foregoing objectives are realized by a tap for coupling electromagnetic energy between a host cable and a second coaxial cable. The tap comprises an impedance transformer, a probe for connecting the impedance transformer to the host cable, a tap cable for connecting the impedance transformer to the second cable, and means defining an inductance coupled in series between the probe and the impedance transformer. A